JP2907518B2 - Thermal recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a thermosensitive recording material, and more particularly, to a thermosensitive recording material capable of obtaining a recorded image capable of preventing falsification.

[Prior art]

The heat-sensitive recording material is generally provided with a heat-sensitive recording layer mainly composed of an electron-donating usually colorless or light-colored dye precursor and an electron-accepting developer on a base material, a heat head, a hot pen, By heating with a laser beam or the like, the dye precursor and the developer react instantaneously to obtain a recorded image, which is disclosed in JP-B-43-4160 and JP-B-45-14039. Such heat-sensitive recording materials have the advantages of being able to record with a relatively simple device, being easy to maintain, and having no noise.They are measurement recorders, facsimile machines, printers, computer terminals, and labels. It is used in a wide range of fields such as ticket vending machines. For example, a payment slip of a financial institution, an air ticket, a ticket, or the like, or a substrate using a base material coated with a magnetic recording layer on the opposite side to the heat-sensitive recording layer, a magnetic ticket, a magnetic commuter pass, There are magnetic coupons, magnetic parking tickets, prepaid (prepaid card) and so on. In the applications exemplified in these, the ticket issuer side has been variously devised as a preventive measure since there is a fear that the ticket issuer may be tampered with in connection with money. As a recording system using a fluorescent substance for the purpose of preventing falsification, there is a thermal transfer recording sheet, and there have been various references. For example, JP-A-59-54598, JP-A-61-228994
And the like. JP-A-59-54598 relates to a heat-sensitive fluorescent transfer medium in which a heat-sensitive transfer ink layer provided on a base material contains a fluorescent pigment and a hot melt adhesive. Here, the fluorescent pigment is used as a colorant, and its purpose is to visually check the hue of the fluorescent pigment and to identify strong fluorescence. However, there is a disadvantage that it is difficult to visually confirm the hue of the fluorescent pigment itself. In addition, in order to be able to visually check, a large amount of fluorescent pigment must be contained, which increases the cost. JP-A-61-228994 discloses a heat transfer recording medium in which a heat-meltable ink layer mainly containing a colorant, a wax, a binder and a softener is provided on a heat-resistant support. The present invention relates to a thermal transfer recording medium characterized by containing a fluorescent substance and using, as a coloring agent, a substance which absorbs little or no fluorescence of the fluorescent substance.
Here, it is an object of the present invention to solve the disadvantage that the fluorescence of the fluorescent substance is absorbed by the colorant and the fluorescence intensity is reduced. The colorant exemplifies that the combination of the fluorescent substance and the same color system is good. Specifically, a red-based colorant is exemplified as a red-based fluorescent substance, and a blue-based and yellow-based are similarly illustrated. That is, in the publication, the same color system has a characteristic in combination, and there is no combination of different color systems.
Further, there is no description corresponding to a black recorded image.

[Problems to be solved by the invention]

In a thermal transfer recording sheet in which a heat-resistant layer is coated on one surface of a substrate and a heat-fusible ink layer is coated on the opposite surface, an example in which a fluorescent substance is contained in the heat-fusible ink is described in the above reference. As described above, there are various problems. However, the examples given here relate to thermal transfer recording, and are intended to contain a fluorescent pigment in the heat-fusible ink.

[Means for Solving the Problems]

The present inventors have conducted intensive studies and, as a result, have provided a thermosensitive recording material capable of preventing tampering. That is, the heat-sensitive recording material provided by the present invention is, in a heat-sensitive recording material containing a dye precursor and a developer that causes the dye precursor to form a color when heated, between the substrate and the heat-sensitive recording layer, 400 to 700nm
And an undercoat layer containing a white or pale white inorganic fluorescent pigment having the maximum emission wavelength. Further, the heat-sensitive recording material provided by the present invention has a base material provided by coating a magnetic recording layer mainly composed of ferromagnetic magnetic powder on a surface opposite to the heat-sensitive recording layer. Inorganic fluorescent pigment of the present invention, CaS: Bi, SrS: Sm: Ce, Zn
S: Ag, ZnS: Cu, ZnS: Sulfide composed of Cu: Co, Sr ₅ (Po ₄ ) ₃
Cl: Eu, 3 (Ba, Mg) 8Al ₂ O ₃ : Eu, ZnO: Zn, Zn ₂ SiO ₄ : M
n, Zn ₂ CeO ₄ , Mn, YVO ₄ : Eu, Y ₂ O ₂ S: En, 0.5MgF ₂ : 3.5MgO
· GeO _2: is characterized in using at least one oxygen acid salt system consisting of Mn. Further, the undercoat layer provided between the base material and the heat-sensitive recording layer is characterized by using an inorganic fluorescent pigment and an inorganic and / or organic pigment. Hereinafter, the present invention will be described specifically. The heat-sensitive recording material of the present invention is used for recording applications that may be falsified, such as payment slips for financial institutions, air tickets,
Tickets, checks, securities, etc. or a base material with a magnetic recording layer coated on the surface opposite to the surface on which the heat-sensitive recording layer is coated. , Magnetic coupon,
It is intended to be used for applications such as magnetic parking tickets, voting tickets such as horse races, bicycle races, and auto races, and prepaid cards (prepayment cards). At present, various precautionary measures have been taken for these money-related items since they are likely to be tampered with on a regular basis. In general, black is often used for images recorded by a thermosensitive recording material. In order to prevent tampering, it is meaningless to be able to visually check the tampering prevention measures. The inorganic fluorescent pigment of the present invention is contained in the undercoat layer between the heat-sensitive recording layer and the substrate, and has the same color as the coating layer of the undercoat layer because the fluorescent pigment is white or pale white, The heat-sensitive recording material of the present invention was completed by paying attention to the fact that it could not be visually confirmed because it was covered with the heat-sensitive recording layer. In addition, the inorganic fluorescent pigments used are:
When illuminated with light of a specific excitation wavelength such as black light (365 nm wavelength), it has an emission color such as blue, green, or red, and its emission maximum wavelength is 400 to 700 nm. This is because it cannot be visually confirmed with visible light. The feature of using the thermal recording material of the present invention is the identification of the thermal recording material after printing. That is, a printed image is obtained when the energy applied by the thermal head is applied to the thermosensitive recording material. However, when light of a specific excitation wavelength such as a black light is irradiated, only the printed image portion exhibits fluorescence and can be identified. It is. The reason for this is that the heat applied to the heat-sensitive recording layer melts the coating layer, the melt sinks into the undercoat layer, the printed portion is depressed, and the undercoat layer is exposed. When the exposed portion is irradiated with black light, the fluorescent pigment contained in the undercoat layer emits light and can be identified. The inorganic fluorescent pigment in the undercoat layer is an inorganic pigment,
It is characterized in that it is contained in an amount of 0.5 to 30% by weight in a composition mainly composed of an organic pigment.
When the content is less than 0.5% by weight, it is difficult to identify when irradiating light of a specific excitation wavelength such as black light. On the other hand, when it exceeds 30% by weight, the oil absorbing effect of the undercoat layer cannot be sufficiently exerted. Also,
It also causes cost increase. Subsequently, the heat-sensitive recording material of the present invention is characterized by using a base material provided with a magnetic recording layer containing ferromagnetic magnetic powder as a main component on the surface of the base material opposite to the surface on which the heat-sensitive recording layer is coated. It is assumed that. The heat-sensitive recording material is capable of magnetically recording a specific signal on a coated magnetic recording layer using a magnetic head, and reading the recording with a magnetic head as needed. The magnetically recorded signal is taken out as an electric signal, and various automatic devices can be operated. In addition, data can be stored in conjunction with a computer. In the case of using this substrate, prevention of tampering is an important issue as seen in the various applications described above. The composition of the above magnetic recording layer comprises a magnetic powder, a binder and other additives. Magnetic powders include γ-Fe ₂ O ₃ , Fe ₃ O ₄ , γ-Fe ₂ O ₃ and Fe ₂
Mixed crystal of O _4, Co-containing γ-Fe ₂ O _3, Co-containing Fe ₂ O _4, Ba- ferrite also Sr-but ferrite is used, a higher coercive force of Ba- ferrite, Sr-ferrite is preferred . As the binder, polyester resin, vinyl chloride resin, polyurethane resin, vinyl chloride-vinyl acetate copolymer, vinyl chloride-acrylonitrile copolymer, styrene-butadiene copolymer, polyacrylate resin, epoxy resin, nitrocellulose, etc. Is used. As other additives, plasticizers, lubricants, antistatic agents, pigments and the like are used as necessary. Examples of the pigment used for the undercoat layer include polyethylene, polystyrene, ethylene-vinyl acetate, and urea.
Organic pigments such as formaldehyde resin and diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, etc. The inorganic pigments to be used are listed, and these can be used alone or in combination of two or more. Among them, oil absorption 70ml / 100
Pigments of g or more, especially calcined kaolin and silicon oxide, are preferred pigments. The dye precursor used in the present invention is not particularly limited as long as it is generally used in pressure-sensitive recording paper or heat-sensitive recording paper. Specific examples are as follows: (1) Triarylmethane compound 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone), 3,3-bis (p-dimethylamino) Phenyl (phthalide, 3- (p-dimethylaminophenyl) -3- (1,
2-dimethylindol-3-yl) phthalide, 3-
(P-dimethylaminophenyl) -3- (2-methylindolen-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindole-3
-Yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-
Bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide,
3-bis (2-phenylindol-3-yl) -5
Dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6-dimethylaminophthalide, etc. (2) Diphenylmethane compounds 4,4'-bis-dimethylaminophenylbenz Hydryl benzyl ether, N-halophenyl leuco auramine, 2,4,5-trichlorophenyl leuco auramine and the like. (3) Xanthene compounds Rhodamine B Anilinolactam, Rhodamine Bp-
Chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-
Octylaminofluoran, 3-ditylamino-7-
Phenylfluoran, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-chloro-7-methylfluoran, 3-diethylamino-7- (3,4-dichloroanilino) fluoran, 3-diethylamino-7
-(2-chloroanilino) fluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3- (N
-Ethyl-N-tolyl) amino-6-methyl-7-anilinofluoran, 3-piperidino-6-methyl-7-anilinofluoran, 3- (N-ethyl-N-tolyl) amino-6 Methyl-7-phenethylfluoran, 3-diethylamino-7- (4-nitroanilinofluoran,
3-dibutylamino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-propyl) amino-6
Methyl-7-anilinofluoran, 3- (N-ethyl-
N-isoamyl) amino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluoran, 3- (N
-Ethyl-N-tetrahydrofuryl) amino-6-methyl-7-anilinofluoran and the like. (4) Thiazine-based compounds benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue and the like. (5) Spiro compound 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho- (3-methoxybenzo) ) Spiropyran, 3-propylspirobenzopyran and the like, and these can be used alone or as a mixture of two or more. As the developer used in the present invention, an electron-accepting substance generally used for heat-sensitive recording paper is used. In particular, a phenol derivative, an aromatic carboxylic acid derivative or a metal compound thereof, N, N′-diarylthio Urea derivatives and the like are used. Particularly preferred among them are phenol derivatives, specifically, p-phenylphenol, p-hydroxyacetophenone, 4-hydroxy-4′-methyldiphenylsulfone, 4-hydroxy-4′-isopropoxydiphenylsulfone, 4-hydroxy-4'-benzenesulfonyloxydiphenylsulfone, 1,1-bis (p
-Hydroxyphenyl) propane, 1,1-bis (p-hydroxyphenyl) pentane, 1,1-bis (p-hydroxyphenyl) hexane, 1,1-bis (p-hydroxyphenyl) cyclohexane, 2,2-bis (P-hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) butane, 2,2-bis (p-hydroxyphenyl) hexane, 1,1-bis (p-hydroxyphenyl)
-2-ethylhexane, 2,2-bis (3-chloro-4-
Hydroxyphenyl) propane, 1,1-bis (p-hydroxyphenyl) -1-phenylethane, 1,3-di [2
-(P-hydroxyphenyl) -2-propyl] benzene, 1,3-di [2- (3,4-dihydroxyphenyl) -2
-Propyl] benzene, 1,4-di [2- (p-hydroxyphenyl) -2-propyl] benzene, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenylsulfone, 3,3'-dichloro- 4,4'-dihydroxydiphenylsulfone, 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone, 3,3'-dichloro-4,4'-dihydroxydiphenylsulfide, 2,2-bis (4-hydroxy Phenyl) methyl acetate 2,2-bis (4-hydroxyphenyl) butyl acetate, 4,4'-thiobis (2-t-butyl-5-methylphenol), bis (3-allyl-4-
Hydroxyphenyl) sulfone, 4-hydroxy-4 ′
-Isopropyloxydiphenylsulfone, 3,4-dihydroxy-4'-methyldiphenylsulfone, benzyl p-hydroxybenzoate, chlorobenzyl p-hydroxybenzoate, propyl p-hydroxybenzoate, p-
Examples thereof include butyl hydroxybenzoate, dimethyl 4-hydroxyphthalate, benzyl gallate, stearyl gallate, salicylanilide, and 5-chlorosalicylanilide. Other thermosensitive recording layers include, as pigments, diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, urea-formalin resin, etc. As additives for further improvement, waxes such as N-hydroxymethyl stearamide, stearamide, palmitamide, naphthol derivatives such as 2-benzyloxynaphthalene, p-benzylbiphenyl, 4-allyloxybiphenyl and the like Biphenyl derivative of 1,2-bis (3-methylphenoxy) ethane, 2,2
Polyether compounds such as 2′-bis (4-methoxyphenoxy) diethyl ether and bis (4-methoxyphenyl) ether, diphenyl carbonate, dibenzyl oxalate,
Carbonic acid or oxalic acid diester derivatives such as oxalic acid di (p-fluorobenzyl) ester can be added. In addition, zinc stearate, metal salts of higher fatty acids such as calcium stearate, paraffin, paraffin oxide, polyethylene, polyethylene oxide, stearamide,
A wax such as caster wax, a dispersant such as dioctyl sodium sulfosuccinate, an ultraviolet absorber such as a benzophenone type or a benzotriazole type, a surfactant, and a fluorescent dye are added as required. In the present invention, as the adhesive used for the undercoat layer and the heat-sensitive recording layer, various kinds of adhesives which are usually used can be used. For example, starches, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol sodium polyacrylate, acrylamide / acrylate copolymer acrylamide / acrylate / methacrylic acid ternary Water-soluble adhesives such as copolymers, alkali acids of styrene / maleic anhydride copolymers, alkali salts of ethylene / maleic anhydride copolymers, polyvinyl acetate, polyurethane, polyacrylate, styrene / butadiene copolymer And latexes such as acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer and ethylene / vinyl acetate copolymer. As the substrate used in the present invention, paper is mainly used, but nonwoven fabric, plastic film, synthetic paper, metal foil, or the like, or a sheet in which a pigment or the like is applied thereto, or a composite sheet obtained by combining these is optionally used. Can be.

[Action]

The heat-sensitive recording material of the present invention, between the substrate and the heat-sensitive recording layer,
It is to be provided with an undercoat layer containing a white or pale white inorganic fluorescent pigment having an emission maximum wavelength of 400 to 700 nm, by containing an inorganic fluorescent pigment in the undercoat layer, It is used as a thermosensitive recording material capable of preventing tampering. As for the anti-tampering property, the inorganic fluorescent pigment is contained in the undercoat layer, and the heat-sensitive recording layer is coated on the undercoat layer. Cannot be identified under light. The heat-sensitive recording material of the present invention can distinguish fluorescent light emission only from a printed image using a thermal head. This is because the heat of the thermal head melts the heat-sensitive recording paper, the melt sinks into the undercoat layer, and the printed portion is depressed from the heat-sensitive recording layer. The inorganic fluorescent pigment in the exposed undercoat layer is used. Can be visually identified under black light. For the above reasons, the heat-sensitive recording material of the present invention has an action not seen in the prior art.

【Example】

Hereinafter, the present invention will be described specifically with reference to examples. Embodiment 1 a. Preparation of Coating Liquid for Undercoat Layer A mixture having the following composition was stirred to prepare a coating liquid for the undercoat layer. The inorganic fluorescent pigment used here has a white powder having a particle diameter of 2.2 μm, an emission maximum wavelength of 624 nm, and a red emission color, and has a composition of Y ₂ O ₂ S: Eu. Inorganic fluorescent pigment 15 parts Calcined kaolin 85 parts Styrene butadiene copolymer latex (50%) 24 parts Phosphated starch (10%) 60 parts Water 52 parts b. Preparation of Heat-Sensitive Coating Solution Liquids A and B were prepared by pulverizing and dispersing a mixture having the following composition with a sand mill until the average particle size became about 1 μm. Liquid A 3-Dibutylamino-6-methyl-7-anilinofluoran 40 parts 10% aqueous polyvinyl alcohol solution 20 parts Water 40 parts Liquid B bisphenol A 50 parts Benzyloxynaphthalene 50 parts 10% aqueous polyvinyl alcohol solution 50 parts Water 100 parts Next, a heat-sensitive coating liquid was prepared using the prepared liquid A and liquid B with the following composition. Liquid A 50 parts Liquid B 250 parts Zinc stearate (40% dispersion) 25 parts 10% aqueous polyvinyl alcohol solution 216 parts Calcium carbonate 50 parts Water 417 parts c. Preparation of heat-sensitive recording material Using each of the above coating solutions, a basis weight of 40 g /
It was applied to the base paper of m ^2, and then a heat-sensitive recording material comprising a coating amount as follows. Undercoat layer 8 g / m ² Thermal recording layer 5 g / m ² d. Print evaluation About the heat-sensitive recording material obtained above, processed so as to be 400-500 seconds in Beck's smoothness with a super calendar,
Dot density of 8 with GIIIFAX testing machine (TH-PMD manufactured by Okura Electric)
Using a thermal head with a dot / mm and a head resistance of 1300Ω, a character image was printed at a head voltage of 22 V and a conduction time of 1.0 ms. Characters printed on the thermosensitive recording material could be identified only as black characters by visible light. Subsequently, when this printed sample was irradiated with a fluorescent inspection lamp (manufactured by Tokyo Optical Machine Co., Ltd., Model F1-3S) in a dark room, a bright red character image could be identified. In addition, since the unprinted portion without a character image was covered with the heat-sensitive recording layer, no fluorescent coloring could be identified. Separately, when the printed portion was observed with an optical microscope, it was clear that the printed portion was in a collapsed state due to thermal fusion as compared with the unprinted portion.

【The invention's effect】

The heat-sensitive recording material of the present invention is capable of discriminating a luminescent color according to the type of the inorganic fluorescent pigment when irradiating light of a specific excitation wavelength such as black light only in a printed image portion using a thermal head. It has a falsification preventing effect and is of extremely high practical value.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41M 5/18-5/34

Claims (4)

(57) [Claims] 1. A thermosensitive recording material containing a dye precursor and a color developing agent for developing the color of the dye precursor upon heating, wherein a white light having an emission maximum wavelength of 400 to 700 nm is provided between the substrate and the thermosensitive recording layer. Alternatively, a thermosensitive recording material comprising an undercoat layer containing a pale white inorganic fluorescent pigment. 2. An inorganic fluorescent pigment comprising CaS: Bi, SrS: Sm: Ce, Z
Sr ₅ (PO ₄ ), a sulfide system consisting of nS: Ag, ZnS: Cu, ZnS: Cu: Co
₃ Cl: Eu, 3 (Ba, Mg) 8Al ₂ O ₃ : Eu, ZnO: Zn, Zn ₂ SiO ₄ : M
n, Zn ₂ GeO ₄ : Mn, YVO ₄ : Eu, Y ₂ O ₂ S: Eu, 0.5MgF ₂・ 3.5MgO
_2. The heat-sensitive recording material according to claim 1, wherein the heat-sensitive recording material is at least one of oxyacid salts based on GeO ₂ : Mn. 3. The heat-sensitive recording material according to claim 1, wherein the undercoat layer comprises an inorganic fluorescent pigment and an inorganic and / or organic pigment. 4. The heat-sensitive recording material according to claim 1, wherein the base material is provided with a magnetic recording layer containing ferromagnetic magnetic powder as a main component on the surface opposite to the heat-sensitive recording layer.